Sensitive percussion fuse



Jan, 2@, 1942. E Q D 2,27@,342

SENSITIVE PERCUSSION FUSE Filed March 30, 1938 2 Sheets-Sheet 1 Jan.2(0), 1942. L. E. REMONDY 2,27@,312

SENSITIVE PERCUSSION FUSE Filed March 30, 1938 2 Sheets-Sheet 2 I ll,

Patented Jan. 20, 1942 SENSITIVE PERCUSSION FUSE Lon Emile Rmondy,

Leonie Arbey and Georges Henri Rmondy, representatives of said Lon EmileRmondy, de-

ceased Paris, France; Marie Application March 30, 1938, Serial No.199,034 In France December 20, 1937 Claims.

The present invention relates to a percussion fuse device forprojectiles, characterised by the fact that the striker, that is to say,the element whereof the impact against the percussion cap produces theignition of the latter, possesses normally and at any moment a certainfaculty of free movement within the interior of the fuse.

It may be said in a way that the striker is floating.

According to the constructions and to the conditions of use, the freemovement under consideration may be temporarily limited and reduced forreasons of safety, but, of course, it is never completely suppressed; itis this latter fact that essentially differentiates the fuse deviceconcerned from other already known fuse devices.

Due to the arrangement under consideration, the striker, which at thedeparture of the shot is applied to the percussion cap withoutpercussion and simply by inertia, is capable of travelling freelytowards the front in proportion as the velocity of the projectile inwhich it is mounted diminishes under the influence of the resistance ofthe air.

When, on the contrary, the projectile encounters an obstacle, the shockproduced drives the striker by inertia towards the percussion cap with aforce depending upon the relative value of the mass of said striker withrespect to the mass of the obstacle encountered.

The striker in fact instantaneously loses its velocity, while theprojectile and the percussion cap secured to the latter continue totravelforwardly at least for a certain time, however short.

In view of the fact that by reason of its constitution, however, themass of the striker may be as low as is necessary, it will beappreciated that the ratio between this mass and that of any obstacle,of a magnitude as limited as it is possible to imagine (an aircraftfabric for example), may always and in any circumstance whatsoever befixed a priori at a value such that the velocity with which the strikeris projected rearwardly for a given minimum residual velocity of theprojectile is sufiicient to produce the violent impact of the strikeragainst the percussion cap necessary to ensure in all cases the ignitionof the latter.

It follows that the device according to the invention makes it possibleto construct an extremely simple and sensitive fuse capable of beingused in the most diverse cases.

Of course, the principal means indicated above may be combined, in thedifferent forms of construction which may be contemplated, with anyother additional means for facilitating its operation or foradditionally providing the desired safety conditions.

It is possible more particularly to so dispose the striker and determineits form as to benefit in the best manner by the non-negligible effectsof the action of the air in the interior of the fuse.

It is possible, in addition, to provide, as accessory devices forlimiting and temporarily reducing the free movement of the striker,auxiliary members which disappear on account of a rise in temperature oron account of a dislocation resulting from the action of the centrifugalforce or from any other action.

Various constructions of the invention have been shown in theaccompanying drawings and described hereinafter byway of example, but ofcourse the constructions concerned may, if necessary, be completed byany useful accessory device or may be modified in their details ofconstruction without departing for that purpose from the scope of theinvention.

In these drawings, Figures 1, 2 and 3 are axial sectional views of oneform of fuse embodying the present invention with the striker shown infull, these figures showing the positions which the members of thedevice occupy first of all at rest, then after a certain time of flightof the projectile on which the fuse is mounted, and finally on impact.

Figures 4 and 5 are similar sectional views of two analogousconstructions in which, however, the strikers have forms different fromthe purely cylindrical form shown in Figures 1, 2 and 3.

Figure 6 is a sectional view similar to Figure 1 showing a modified formof the fuse illustrated in Figure 1, including a safety member.

Figures 7 and 8 are plan and sectional views, respectively, of thesafety member of Figure 6, the section of Figure 8 being takensubstantially on the line VIIIVIII of Figure 7.

Figure 9 is an axial sectional view of a construction in which theobturation diaphragm of the preceding constructions is replaced by acapsule fixed in position by a pin which ruptures on impact.

Figure 10 is a similar sectional view of a modified construction inwhich the said capsule is resiliently mounted on the front part of thefuse.

As will be seen in these figures, and particularly in Figures 1, 2 and3, the striker 1, in the present case formed by a simple cylinder ofsuitable dimensions, is free to move between the percussion cap 2 lodgedin the. interior of the fuse body 3 and a flexible diaphragm 4 crimpedin the front end of the fuse, said diaphragm closing the front of acavity iwhich, at the momentof impact, permits the diaphragm 4 todeformfreely and without appreciable resist-.

ance. I I

When at rest and in normal times, the fulminating composition of thepercussion cap is protected from the friction of the striker either 'bythe. end 6 of said percussion cap, if the latter is placed as .shownwith its orifice directed towards the interior of the projectile, or bya light plate of suitable thickness and strength,

Furthermore, for preventing the fuse under ground, two indispensableprecautions must, of

course, be taken.

'In the first place, it is necessary to limit the length of the strikerto a value less than that of the cylindrical recess or bore a in whichthe striker is free to move.

true shock which by inertia drives it violently to the rear and produceson the percussion cap a percussion sufiicient to causethe immediatedeflagration of the latter.

In view of the low resistance of the diaphragm 4' and the low weight of.the striker, the shock on 'consi-deratio'nfrom operating under theaction I latter a slightly conical form as'shown in Fig In addition, itis likewise necessary to limit the I diameter of the aforesaidrecess andconsequently that of the striker to a value such that any foreign bodyof really appreciable mass will be ,un-

able, after having destroyed and passed'through the diaphragm, to enterthe said recess-5a and continue to force back the'striker against thepercussion cap.

There is furthermore provided inthe fuse body 3 an air escape passage 1closed by a light airtight plug a. I

The, operation of the device is extremely simple to understand.

'Upon the departure-of the shot (1st position) the striker l,irrespective of the position which it occupies at rest in its recess, isapplied by the action of the acceleration imparted to th projectile andby inertia, but without violent shock, against the percussion cap asshown in Figure 1.

In fact, in view of the extremely low mass which can be given to thesaid striker on account of its exceptionally simple form, the pressureof static order exerted by said striker on the percussion cap upon thedeparture of the shot is very low, even in the case of the maximumaccelerations normally considered in practice.

From this point of view, it is necessary to consider that, at thedeparture of the shot, the acceleration is always gradual and cannot becompared with a true shock.

Furthermore, as a measure of safety, the striker has not been given apointed form.

As soon as it leaves the gun-barrel and is free from the gaseous masswhich accompanies it for several instants, the projectile graduallyloses its velocity under the influence of the resistance opposed to itby the air.

The striker, on the contrary, which is not subject to any resistance onthe part of the air, retains its velocity and travels slowly towards thefront of the projectile until, as shown in Figure 2, its front end bearsagainst the diaphragm 4 (2nd position).

Matters then remain as they are until the impact is produced.

The instant the latter takes place, the diaphragm 4 which is extremelyflexible is deformed and instantaneously transmits to the striker aimpact, even against an extremely light obstacle of little. resistance,such as the surface of an aeroplane wing or the fabric of aballoon, issufii-, cient as shown in Figure 3 for the striker (3rd position) to acton the base of the percussion cap or. on theprotecting plate abovereferred to after the manner of a veritable solid punch or even'of asocket punch, and thus produce by local heating the deflagration of thefulminating substance of the percussion cap.

To facilitate the movements of the striker in its recess, itis possibleif necessary to give to the ure 4. I

' i Furthermore, since in such a .fuse the relative values of the massof the striker, the resistance of the diaphragm and the resistance ofthe base of the percussion cap, or of the protective plate whichreplaces it in certain cases, play. an ex tremely important part, it ispossible in order .to adapt the mass of thestriker to certaincon cretecases to give it a form such as that in which I I I it is shown inFigure 5, wherein will be seen a striker having its front part .la of agreater diameter than that of the part lb. I

r ,This arrangement furthermore favours the ad- I 'vantageous actionexerted on the striker by the air which is situated in the cavity 5 andwhich,

forced back by the diaphragm ,4 at. the moment of impact,escapes throughtheescape passage I. The action of the air under consideration mayfurthermore be accentuated by increasing the relative size of the cavity5 in the desired manner, for example in accordance with what will beindicated below in connection with the constructions shown in Figures 9and 10.

Figure 6 shows a construction similar to that just described, butwherein there has been provided by way of additional safety, between thestriker I and the diaphragm 4, a washer 9, the detail of which is shownin Figures 7 and 8.

Said washer, which is adapted to break up very rapidly either under theaction of heating due to the friction of the air or under the action ofthe centrifugal force after the projectile carrying the fuse has leftthe gun-barrel, is intended to reduce at rest the space within which thestriker I may move freely and to prevent; the said striker from comingprematurely into contact with the diaphragm 4.

Due to the presence of the washer under consideration, the said strikerduring the handling of the projectile, or during the first instants ofthe flight of the latter, can never assume even under the effect of ashock an acceleration sufiicient to strike effectively against thepercussion cap and produce the detonation thereof.

As will be seen in Figures 7 and 8, the washer 9, for facilitating itsbreaking up under the action of the centrifugal force, comprises athickened edge portion Ill which so to speak acts as a flywheel andtends to increase the internal forces intended to produce the rupture ofthe piece as soon as the latter, driven by the projectile, rotates at asufficient speed.

Finally, if necessary, the said washer may comprise slots I2 likewiseintended for facilitating its rupture.

In the constructions shown respectively in Figures 9 and 10, a means hasbeen sought for increasing the driving action of the air on the striker.

For this purpose, in the construction of Figure 9, the diaphragm 4 hasbeen replaced by a capsule l3 normally held in position by a pin l4 andprovided in its upper part with an air-tight joint l5.

In order to escape, the air contained in the cavity 5 has certainly twooutlets, on the one hand that offered to it along the striker andthrough the escape passage 7, and on the other hand that situated alongthe lateral wall If of the capsule l3; however, the bafiie arrangementwhich this lateral wall It offers to the passage of the air diminishes,in regard to the latter, the possibilities of escape by that path.

Consequently, the air under consideration exarts its principal action onthe striker and is associated with the shock applied to it through themedium of the capsule I3 for bringing it violently from the position inwhich it is shown in dotted lines to the percussion position in which itis shown in solid lines.

In the construction shown in Figure 10, the capsule or cap [3 is held onthe fuse by a flange H which prevents it from coming out and which atthe same time acts as an air-tight packing. A light spring l3 maintainsit in its advanced position until the moment at which the impact isproduced.

From the point of view of the action of the air, it is possible torepeat in this connection what was said above with reference to theconstruction shown in Figure 9.

As the movement of the striker would be excessive from the practicalpoint of view if it was allowed in this particular case to come intocontact with the capsule which is intentionally very remote from thehead of the fuse in order to increase the volume of the chamber 5 andthe quantity of air forced back, said movement is limited by means of acollar I9 which is movable in a bore 2!) and which, during the flight ofthe projectile, is arrested by the flange 2 I.

At this moment and in accordance with what is shown in dotted lines inthe figure, the front of the striker projects sufficiently into thechamber 5 in front of the fuse head to enable the capsule l3, uponimpact, to apply to it the necessary shock.

What is claimed is:

1. In a percussion fuse for projectiles of the extra-sensitive type, afuse body having an axial bore extending rearwardly from the forward endthereof, a striker member movable in said bore, a percussion cap fixedlymounted in said fuse body adjacent the rear end of said bore, and aclosure member associated with the forward end of said fuse body havingat least a portion thereof movable rearwardly upon impact of theprojectile with an obstacle while in flight to contact said strikermember and at least momentarily decrease the forward velocity of thelatter relatively to that of the projectile, whereupon the inertia ofsaid striker member and the continued forward progress of saidpercussion cap at the residual velocity of the projectile bring saidstriker member and cap into contact with one another with sufficientforce to effect ignition of the fuse, said striker member being at alltimes freely movable into contact with said percussion cap, but itslength being less than the length of said bore, and said striker and capmembers being so constructed and arranged, and the mass of said strikermember being such, that detonation of said cap member will not occurupon set back due to firing of the projectile.

2. In a percussion fuse for projectiles of the extra-sensitive type, afuse body having an axial bore extending rearwardly from the forward endthereof, a percussion cap fixedly mounted in said fuse body adjacent therear end of said bore and having a deformable protective covering overthe forward surface thereof, a striker member of a length less than thatof said bore slidably mounted in the latter and free to move thereininto contact with the protective covering of said percussion cap whethersaid projectile be at rest or in fiight, and a deformable closure memberassociated with the forward end of said fuse body and operable upondeformation to contact said striker member and efiect a relativemovement between the latter and said fuse body such as tends to bringsaid striker member and percussion cap into contact with one another,the mass of said striker member and the extent of its free movementbeing so proportioned relatively to the resistances to deformation ofsaid closure member and percussion cap covering that the force exertedby said striker member upon said percussion cap covering due to saidmovement is in sufficient to effect ignition of the fuse except whensaid closure member is deformed by impact of the projectile with anobstacle while in flight.

3. In a percussion fuse for projectiles of the extra-sensitive type, afuse body having a cavity formed in the forward end thereof and an axialbore extending rearwardly from said cavity, a flexible diaphragm closingthe forward end of said cavity, a percussion cap fixedly mounted in saidfuse body adjacent the rear end of said bore, and a striker member of alength less than that of said bore slidably mounted in the latter and.free to move therein into contact with said percussion cap and throughat least a portion of the distance between said cap and said diaphragmwhether said projectile be at rest or in flight, said diaphragm beingdeformable upon impact of the projectile with an obstacle while inflight to contact said striker member and at least momentarily decreasethe forward velocity of the latter relatively to that of the projectile,whereupon the inertia of said striker member and the continued forwardprogress of said percussion cap at the residual velocity of theprojectile bring said striker member and cap into contact with oneanother with sufficient force to effect ignition of the fuse, saidstriker and cap members being so constructed and arranged, and the massof said striker member being such, that detonation of said cap memberwill not occur upon set back due to firing of the projectile.

4. In a percussion fuse for projectiles of the extra-sensitive type, afuse body having a cavity formed in the forward end thereof, apercussion cap fixedly mounted in said fuse body rearwardly of saidcavity and having a deformable protective covering over the forwardsurface thereof, an axial bore in said fuse body of substantiallysmaller diameter than and leading from said cavity to said percussioncap, a striker member of a length less than that of said bore slidablymounted in the latter and free to move therein into contact with theprotective covering of said percussion cap whether said projectile be atrest or in flight, and a closure member closing the forward end of saidcavity and movable rearwardly upon impact to contact said striker memberand effect a relative movement between the latter and said' fuse bodysuch as tends to bring said striker member and percussion cap intocontact with one another, the mass of said striker member and the extentof its free movement-being so proportioned relatively to the resistancesto movement and deformation of said closure member and percussion capcovering that the force exerted by said striker member upon saidpercussion cap covering due to said movement is insufficient to effectignition of the fuse except when said closure member is moved rearwardlyby impact of the projectile with an obstacle while in flight.

5. In a percussion fuse for projectiles of the extra-sensitive type, afuse body having a cylindrical bore extending rearwardly from theforward end thereof, a percussion cap fixedly mounted in said fuse bodyadjacent the rear end of said bore and having a deformable protectivecovering over the forward surface thereof, a non-pointed,cylindrical'striker member of a length less than that of said borehoused within the latter and at all times freely movable therein intocontact with the protective covering of said percussion cap, and adeformable closure member closing the forward end of said fuse body andoperable upon deformation to contact said striker member and effect arelative movement between the latter and said fuse body such as tends tobring said striker member and percussion cap into contact with oneanother, the mass of said striker member and the extent of its freemovement being so proportioned relatively to the resistances todeformation of said closure member and percussion cap covering that theforce exerted by said striker member upon said percussion cap coveringdue to said movement is insuficient to effect ignition of the fuseexcept when said closure member is deformed by impact of the projectilewith an obstacle while in flight.

6. In a percussion fuse for projectiles of the extra-sensitive type, afuse body having a cavity formed in the forward end thereof, a flexiblediaphragm closing the forward end of said cavity, a percussion capfixedly mounted in said fuse body rearwardly of said cavity, acylindrical bore of substantially smaller diameter than and leading fromsaid cavity to said percussion cap, and a non-pointed, cylindricalstriker member of a length less than that of said bore slidably mountedin the latter and at all times free to move therein into contact withsaid percussion cap and through at least a portion of the distancebetween said cap and said closure member, deformation of said diaphragmupon impact of the projectile with an obstacle while in flight beingeffective to contact said striker member and at least momentarilydecrease the forward velocity of the latter relatively to that of theprojectile, whereupon the inertia of said striker member and thecontinued forward progress of said percussion cap at the residualvelocity of the projectile bring said striker member and cap intocontact with one another with sufficient force to effect ignition of thefuse. said striker and cap members being so constructed and arranged,and the mass of said striker member being such, that detonation of saidcap member will not occur upon set back due to firing of the projectile.

7. A percussion fuse according to claim 2, wherein both said bore and.said stroker member are provided with forward portions of largerdiameter than the rearward portions thereof which are adjacent saidpercussion cap.

8. In a percussion fuse for projectiles of the extra-sensitive type, afuse body, a flexible diaphragm closing the forward end of said fusebody and deformable upon impact with an obstacle, a percussion capfixedly mounted in said fuse body rearwardly of said diaphragm, astriker member housed within said fuse body and at all times freelymovable therein into contact with said percussion cap as well as towardsaid diaphragm, the length of said striker member being less than thedistance between said cap and the maximum deformed position of saiddiaphragm, and means normally preventing forward movement of saidstriker member sufficiently to effect contact with said diaphragm at alltimes prior to the firing of the projectile, said means being soconstructed and arranged as to be rendered inoperative under theinfluence of the forces to which it is subjected during the flight ofthe projectile.

9. In a percussion fuse for projectiles of the extra-sensitive type, afuse body, a flexible diaphragm closing the forward end of said fusebody and deformable upon impact with an obstacle, a percussion capfixedly mounted in said fuse body rearwardly of said diaphragm, astriker member housed within said fuse body and at all times freelymovable therein into contact with said percussion cap as Well as towardsaid diaphragm, the length of said striker member being less than thedistance between said cap and the maximum deformed position of saiddiaphragm, and a safety member consisting of a washer normallyinterposed between the forward end of said striker member and saiddiaphragm for preventing forward movement of said striker membersufliciently to effect contact With said diaphragm at all times prior tothe firing of the projectile, said washer having a peripheral portion ofgreater mass than its central portion and being so constructed andarranged as to rupture under the influence of the centrifugal force towhich it is subjected during flight of the projectile.

10. A percussion fuse according to claim 4 wherein said closure memberis bodily slidable rearwardly relatively to said fuse body to compressthe air normally filling said cavity and thereby augment the forcestending to bring said striker member and percussion cap into contactupon impact of the projectile, and which includes yieldable means fornormally holding said closure member in its foremost position untilimpact.

LEON EMILE REMONDY.

